C13 and C15 On-highway Engines Caterpillar

Use this procedure to determine if the circuit for the ignore brake/clutch switch is operating correctly. There are no diagnostic codes for this circuit.

Background Information

Some vehicle applications require mobile use of the vehicle during PTO operation. When the ignore brake/clutch switch is ON, depressing the brake or the clutch will not disengage PTO operation or a set engine speed. If the "Ignore Brake/Clutch Switch" parameter is programmed to "None" (default), this feature is not used. If the "Ignore Brake/Clutch Switch" parameter is programmed to "J1/P1:47", then the feature is available and the switch circuit must be connected to terminal P1-47.

Illustration 1	g00955558
Typical schematic for the ignore brake/clutch switch

Note: The circuit's return may be connected to terminal P1-3, P1-5, or P1-18.

Illustration 2	g01151227
Pin locations on ECM connector (P1-18) Input sensor common 1 (P1-47) Input 5 (Ignore brake/clutch switch)

Test Step 1. Inspect Electrical Connectors and Wiring

1. Thoroughly inspect the ECM vehicle harness connector J1/P1, the connectors, and the firewall bulkhead connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on any wires in the ECM connector that are associated with the circuit for the ignore brake/clutch switch.

3. Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

4. Check the harness and the wiring for abrasion and for pinch points from the ignore brake/clutch switch to the ECM.

   Refer to Illustration 2 for terminal locations for the ECM.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.

Results:

• Yes - The wiring is OK. Proceed to Test Step 2.

• No - The wiring is not OK

  Repair: .Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check the Status of the Ignore Brake/Clutch Switch

1. Connect Caterpillar Electronic Technician (ET) to the data link connector.

2. Turn the ignition key switch to the ON position.

3. Operate the switch in the ON and OFF positions.

4. View the status for parameter "Ignore Brake/Clutch Switch" on Cat ET.

5. If the status for parameter "Ignore Brake/Clutch Switch" indicates "None", then the "Ignore Brake/Clutch Switch" parameter has not been programmed.

Expected Result:

The status screen indicates "On" when the switch is turned on. The status screen indicates "Off" when the switch is turned off.

Results:

• Yes - The switch is operating normally. Continue troubleshooting if the original condition is not resolved.

  STOP

• No - The ECM is not reading the change in switch status. Proceed to Test Step 3.

Test Step 3. Check the Switch Circuit at the ECM

Illustration 3	g01151232
Pin locations on breakout T (18) Input sensor common 1 (47) Input 5 (Ignore brake/clutch switch)

1. Turn the ignition key switch to the OFF/RESET position.

2. Install a breakout T to the ECM vehicle harness connector J1/P1.

3. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

4. Insert the jumper wire into terminal 18 (Input Sensor Common 1) of the breakout T. Insert the other end of the jumper wire into terminal 47 (Ignore Brake/Clutch Switch) of the breakout T.

5. Verify that Cat ET is connected to the data link connector.

6. Turn the ignition key switch to the ON position.

7. Alternately remove the jumper wire and insert the jumper wire at terminal 18 while you monitor the status screen on Cat ET.

Expected Result:

The switch status changes from "On" with the jumper wire in place to "Off" when the jumper wire is removed.

Results:

• Yes - The ECM is functioning properly at this time. Proceed to Test Step 4.

• No - The ECM is not functioning properly.

  Repair: Perform the following repair:

  1. Temporarily connect a test ECM.

  2. Remove all jumpers and replace all connectors.

  3. Recheck the system for active diagnostic codes.

  4. Repeat the test step.

  5. If the problem is resolved with the test ECM, reconnect the suspect ECM.

  6. If the problem returns with the suspect ECM, replace the ECM.

  7. Verify that the repair eliminates the problem.

  STOP

Test Step 4. Insert a Jumper Wire at the Switch

1. Turn the ignition key switch to the OFF/RESET position.

2. Reconnect the ECM vehicle harness connector J1/P1.

3. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

4. Insert the jumper wire between the two terminals of the ignore brake/clutch switch.

5. Turn the ignition key switch to the ON position.

6. Alternately remove the jumper wire and then insert the jumper wire at the switch terminals. At the same time, watch the status screen on Cat ET.

Expected Result:

The switch status changes to "On" with the jumper wire in place to "Off" when the jumper wire is removed.

Results:

• Yes - The harness is OK.

  Repair: Replace the ignore brake/clutch switch.

  Verify that the repair eliminates the problem.

  STOP

• No - There is a problem in the wire harness between the ignore brake/clutch switch and the ECM. Proceed to Test Step 5.

Test Step 5. Insert a Jumper Wire at the Bulkhead Connector

1. Turn the ignition key switch to the OFF/RESET position.

2. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

3. Insert the jumper wire between the two terminals for the ignore brake/clutch switch on the engine side of the bulkhead connector.

4. Turn the ignition key switch to the ON position.

5. Alternately connect and then disconnect the jumper wire. At the same time, monitor the status screen on Cat ET.

Expected Result:

The switch status changes from "On" with the jumper wire in place to "Off" when the jumper wire is removed.

Results:

• Yes - The switch status changes from "On" with the jumper wire in place to "Off" when the jumper wire is removed. The problem is in the vehicle wiring between the bulkhead connector and the switch.

  Repair: Inspect the vehicle wiring and then repair the vehicle wiring. Otherwise, send the vehicle to the OEM dealer for repair.

  Verify that the problem is resolved.

  STOP

• No - The switch status is incorrect. The problem is in the vehicle wiring between the bulkhead connector and the ECM.

  Repair: Inspect the vehicle wiring and then repair the vehicle wiring. Otherwise, send the vehicle to the OEM dealer for repair.

  Verify that the problem is resolved.

  STOP